title: Echocardiographic estimation of pulmonary vascular resistance in chronic thromboembolic pulmonary hypertension: utility of right heart Doppler measurements.
abstract: The ratio of tricuspid regurgitation velocity divided by the velocity-time integral of right ventricular outflow tract pulsed-wave Doppler tracing (TRV/VTI(RVOT) ) has been used to estimate pulmonary vascular resistance (PVR). However, this method has not been validated in chronic thromboembolic pulmonary hypertension (CTEPH). We assessed the utility of TRV/VTI(RVOT) in patients with CTEPH and PVR from 2 to 20 WU. All had right heart catheterization (RHC) within 2 days of echocardiography. TRV/VTI(RVOT) was calculated and RHC-derived pressures, PVR, and cardiac outputs were recorded. Mean pulmonary artery pressure was 47 ± 12 mmHg, cardiac output: 4.2 ± 1.1 L/min, PVR: 9 ± 4 WU, right atrial pressure: 12 ± 6 mmHg. Mean VTI(RVOT) was 13 ± 5 cm; mean TRV was 4.2 ± 0.8 m/s, mean tricuspid regurgitation severity was 2.5 ± 0.8 (1 = trace, 2 = mild, 3 = moderate, 4 = severe). Regression analysis demonstrated a correlation between RHC PVR and TRV/VTI(RVOT) : PVR = 19.4 × (TRV/VTI(RVOT) ) + 2.4 (r = 0.74, P < 0.001). However, Bland-Altman analysis found a poor degree of agreement between echo-derived PVR and RHC PVR. We also studied 28 patients with non-CTEPH pulmonary hypertension. Similar analysis revealed a regression equation of PVR = 20.1 × (TRV/VTIR(RVOT) ) + 0.3 (r = 0.57, P < 0.01).
  
  
  CONCLUSIONS
  TRV/VTI(RVOT) is only marginally useful for estimating PVR in CTEPH (r = 0.74). Moreover, the regression equation in CTEPH differs significantly from previous studies in pulmonary hypertension. Reasons for this may include the markedly elevated PVR levels in this population and specific effects on VTI(RVOT) from CTEPH.
authors.affiliation: U.C. San Diego School of Medicine and Sulpizio Cardiovascular Center, University of California San Diego, La Jolla, CA.
authors.forename: Yu
authors.initials: Y
authors.lastname: Xie
authors.forename: Benita M
authors.initials: BM
authors.lastname: Burke
authors.forename: Alex
authors.initials: A
authors.lastname: Kopelnik
authors.forename: William
authors.initials: W
authors.lastname: Auger
authors.forename: Lori B
authors.initials: LB
authors.lastname: Daniels
authors.forename: Michael M
authors.initials: MM
authors.lastname: Madani
authors.forename: David S
authors.initials: DS
authors.lastname: Poch
authors.forename: Nick H
authors.initials: NH
authors.lastname: Kim
authors.forename: Daniel G
authors.initials: DG
authors.lastname: Blanchard
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015150:Echocardiography, Doppler / Q000379:methods*; D005260:Female; D006801:Humans; D006976:Hypertension, Pulmonary / Q000150:complications / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D008297:Male; D008875:Middle Aged; D011651:Pulmonary Artery / Q000000981:diagnostic imaging / Q000503:physiopathology*; D011652:Pulmonary Circulation; D011655:Pulmonary Embolism / Q000150:complications / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014655:Vascular Resistance; D055815:Young Adult
keywords: Doppler echocardiography; chronic thromboembolic pulmonary hypertension; pulmonary hypertension; pulmonary vascular resistance